Programmable boatlift system with boat position sensor

ABSTRACT

A programmable boatlift system having a cable extending up from one end of a boatlift cradle, across to a shaft attached to a motor, and down to an opposite end of the boatlift cradle. The cable passes through a hole in the shaft. A position sensor having an idler sheave is placed on the cable. The motor winds or unwinds the cable around the shaft to cause the cable to move across the roller sheave to raise or lower the boatlift cradle. The position sensor produces an output signal proportional to the distance the cable travels over the idler sheave as the cable causes the idler sheave to rotate. An electronic control circuit uses the output signal to infer the vertical position of the boatlift cradle and to position the boatlift cradle as desired.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of pending patent application No.11/937,937 filed Nov. 9, 2007, which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a programmable boatlift system, and,more particularly, to a boat lift system that indicates the exactposition of the boat within the lift system.

BACKGROUND OF THE INVENTION

Programmable boat lift systems are known but they require two cables oneach side of the boat, two at the front and two at the rear of the boat.Two motors are required, one for each side of the boat to operate thecables. The use of level sensors is known to stop or start the motors toposition the boat as desired, but these sensors must be placed near theboat and move up and down with the boat. They require the use of mercuryswitches and float switches and can be exposed to water as the boat isplaced into the water. The plurality of motors, cables, and sensors inthese systems create a need for constant maintenance and repair. A cablesystem for a boat lift using a single motor is known but it is notsuitable for detecting the position of the boat within the lift system.

What is needed is a boatlift system that operates with a single motor,with a single cable at the front of the boat, a single cable at the backof the boat, and a simple sensor that measures the actual position ofthe boat within the boat lift, so that a remote, programmable unit canposition the boat automatically as desired.

SUMMARY OF THE INVENTION

The present invention is a boat lift system having a boatlift structurewith a front end, a back end, and vertical and horizontal support beams.Boatlift cradles are positioned among the support beams and areconnected to the upper portion of the boatlift structure by a steelcable at the front of the boatlift structure and a steel cable at theback end of the boatlift structure. The cables extend from one side ofthe cradle upwards towards a pulley, horizontally across the boatliftstructure towards a shaft rotated by a motor, through a hole in theshaft, and downward to the lift cradle. An idler sheave is placed on oneof the cables on the portion that extends horizontally across the boatlift structure. The sheave is fitted with a quadrature encoder toproduce an electronic signal proportioned to the number of rotations ofthe sheave as the cable moves across the sheave during lifting orlowering of the lift cable. The signal from the encoder is sent to anelectronic control circuit which uses the encoder signal to infer thevertical position of the boat or lift cradle within the boatliftstructure. The electronic control circuit consists of a microcontrollerwith non-volatile memory, oscillator, and related circuitry forreceiving and sending electronic signals. The electronic control circuitwill also receive signals from a user input keypad which allows a userto invoke the end functions of the programmable boatlift system, and theelectronic control circuit will send signals to the motor to turn theboat motor on and off, in either direction based upon the programming inthe electronic control circuit. Because the boat position sensorprovides the exact vertical position of the boat within the boatliftstructure, limit sensors, float sensors, moisture sensors, and timersare not required for operation of the boatlift system.

An advantage of the present invention is a programmable boatlift systemthat requires only two cables.

Another advantage is a single boat position sensor which determines theexact position of the boat within the boat structure.

Another advantage is a single motor to raise and lower the boat.

Another advantage is a simple, durable, idler sheave with a quadratureencoder to sense the boat position.

Another advantage is a programmable control unit with a remote controlto automatically position the boat within the boat lift structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the boatlift structure of the programmable boatlift systemof the present invention.

FIG. 2 shows the winch mechanism of the present invention.

FIG. 3 shows the idler sheave with IR detectors engaging the lift cable.

FIG. 4 shows a view of the idler sheave and quadrature encoder viewedalong the length of the cable.

FIG. 5 shows the electronic components of the programmable boatliftsystem.

FIG. 6 shows the electronic components of the electronic controlcircuit.

FIG. 7 is an electrical schematic of the microcontroller of theelectronic control circuit.

FIG. 8 is an electrical schematic of the rotary encoder and connector ofthe boat position sensor.

FIG. 9 is an electrical schematic of the user keypad interface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the boatlift structure 11 of the boatlift system 10 of thepresent invention. The boatlift structure 11 has a front end 12 and aback end 13. The boatlift structure 11 is supported by four verticalbeams 14, and has right side 15 and left side 16. A boatlift cradle 17is suspended by a cable 21 from the upper ends of beams 14. A motor 18is attached to the upper end of a beam 14 at the back end 13 and leftside 16 of the boatlift structure 11. The motor 18 has shaft 19 thatextends from the motor 18 to a bearing 20 attached at the upper end of abeam 14 at the front end 12 and left side 16 of the boatlift structure11. Bearing 20 supports shaft 19 as motor 18 rotates shaft 19.

Cable 21 is attached to one side 22 of boatlift cradle 17 and extendsupward therefrom to pulley 50, from there across to shaft 19, and fromthere down to the opposite side 23 of boatlift cradle 17. A boatposition sensor 24 is attached to boatlift structure 11 and engagescable 21 by means of an idler sheave 25. The boat position sensor 24 isconnected electrically to motor 18 by a wire 28 and to a user key padinterface 27 by a wire 54.

FIG. 2 shows the shaft 19 attached to a beam 14 by a bracket 29 at backend 13, right side 16 of boatlift structure 11. The shaft 19 issupported by bearings 30. Shaft 19 has hole 31 through which cable 21 isinserted. As motor 18 turns the portions of cable 21 extending upwardfrom each side 22, 23 of boatlift cradle 17 are wound around shaft 19 inthe same direction. The portions of the cable attached to sides 22, 23of boatlift cradle 17, thus, lift or lower boatlift cradle 17 in a levelhorizontal position. Although not shown, a similar cable and boatliftcradle arrangement is at the front end 12 of boatlift structure 11,wherein the cable passes through a second hole in shaft 19. Thus, thereare two boatlift cradles, each with its own cable arrangement whereinthe cables lift or lower both boatlift cradles in unison as the motor 18rotates shaft 19 which acts as a winch. With a boatlift cradle at thefront of a boat and at the rear of the boat, the rotation of shaft 19 bymotor 18 will raise and lower the boat in a level position, bothhorizontally and vertically.

FIG. 3 shows the idler sheave 25 of the boat position sensor 24 in placeon cable 21. Sheave 25 rotates on an axle 51. Sheave 25 has a pluralityof holes for transmission of infrared (IR) light which is detected by IRdetectors 53. FIG. 4 shows the boat position sensor 24 looking downlinealong cable 21. FIG. 4 further shows a quadrature encoder 34 in placeover idler sheave 25 and IR transmitters 52. The detection of the IRsignal through holes 32 in the sheave 25, as the sheave 25 is rotated bycable 21, allows the encoder 34 to produce an output signal directlyproportional to the distance cable 21 has traveled as it raises orlowers the boatlift cradle 17. Thus, this output signal is directlyproportional to the absolute amount a boat in the boatlift cradle 17 hasbeen raised or lowered by the cables. The two pairs of IR transmitters52 and receivers 53 are set, preferably, about 165° apart relative toaxle 51 of sheave 25.

FIG. 5 shows a block diagram of the electrical and functional componentsof the programmable boatlift system 10 of the present invention. An ACinlet and power supply circuit 36 interfaces with line voltage andprovides for the power requirements of the circuitry. The power supply36 provides 12 volt line voltage to a motor control circuit 35. A 5 voltline voltage is supplied to an electronic control circuit 26. This 5volt line voltage can operate for a short period of time after externalpower is removed. This will allow the electronic control circuit 26 torecord the boatlift cradle's 17 final absolute position at power-down innon-volatile memory, so as to eliminate the need to recalibrate theboatlift cradle's 17 position when power is restored. Motor controlrelays in the motor control circuit 35 turn the boatlift motor 18 on andoff, in either direction, based upon input from the electronic controlcircuit 26.

The boat or cable position sensor 24 provides an output signal to theelectronic control circuit 26 which uses this signal to infer theabsolute position of the boatlift cradle 17. A user interface or keypad27 allows a user to invoke the function of the programmable boatliftsystem 10 through keys or push buttons. The electronic control circuit26 encompasses all logical operations of the circuitry and interfaceswith the cable position input and user interface/keypad input to controlthe lift motor on/off and direction.

The components of the electronic control circuit 26 are shown in FIG. 6.It consists of a microcontroller 38 with non-volatile memory, anoscillator, and related circuitry to interface with all other parts ofthe circuitry. Electronic control circuit 26 also contains an in-circuitprogramming header 37, a motor control circuit 41, limit switch circuits39, and a buzzer/power loss circuit 40. FIG. 7 shows an electricalschematic of a microcontroller 38. FIG. 8 shows an electrical schematicof the rotary encoder 34 and connector. FIG. 9 shows an electricalschematic of the user keypad 27 and connector. A remote control unit canalso be used to operate the user keypad 27. A user can press up, down,or stop keys to make the boatlift cradle 17 go up or down or stop at anydesired position. An enter key can be used to program the electroniccontrol circuit 26 to raise and lower the boatlift cradle a desiredamount by pressing other keys, such as, for example, keys labeled“winter”, “night”, “water”, etc. The electronic control circuit 26 isprogrammable to automatically turn off the motor 18 after a fixed numberof rotations of the idler sheave 25 in one direction, and after the samefixed number of rotations in an opposite direction, and at any amount ofrotations there between.

The foregoing description has been limited to specific embodiments ofthis invention. It will be apparent; however, that variations andmodifications may be made by those skilled in the art to the disclosedembodiments of the invention, with the attainment of some or all of itsadvantages and without departing from the spirit and scope of thepresent invention. For example, various types of known microprocessing,memory, and programming devices may be used in the electronic controlcircuit. Various types of rotary encoders known in the art may be usedwith the idler sheave. Other emitters and detectors may be used in theencoder besides infrared. The electronic control circuit can beprogrammed to lock after a certain amount of time for security purposes,and a pass code can be entered into the user key pad to unlock theelectronic control circuit. The electronic control circuit can beprogrammed to produce an alarm before the motor is turned on. A wirelessremote device can be used to access the electronic control circuitand/or user key pad. One or more limit switches can be used for safetypurposes to turn off the motor in case of a malfunction in the system.

It will be understood that various changes in the details, materials,and arrangements of the parts which have been described and illustratedabove in order to explain the nature of this invention may be made bythose skilled in the art without departing from the principle and scopeof the invention as recited in the following claims.

1. A programmable boat lift system, comprising: a) a single idler sheavehaving a plurality of holes for the transmission of light, said idlersheave constructed to engage a single cable and to rotate on an axis asthe single cable moves across said idler sheave; b) a quadrature encoderhaving two pairs of IR transmitters and IR receivers, said encoderplaced over said idler sheave, said two pairs of IR transmitters and IRreceivers being set apart about 165 degrees relative to said axis ofsaid idler sheave; c) said IR transmitters transmitting infra red lightthrough the holes in said idler sheave and said IR receivers receivingsaid infra red light so that said encoder produces an electronic outputsignal in proportion to the number of rotations of said idler sheave,and in proportion to the distance the single cable travels over saididler sheave, as the single cable moves across said idler sheave; and d)an electronic control circuit having a microcontroller, an in-circuitprogramming header; and a motor control circuit, said control circuitprogrammable to use said output signal to infer the exact position ofthe single cable and the boat lift cradle without the requirement of alimit switch.
 2. The boat lift system of claim 1 wherein said electroniccontrol circuit is programmable to automatically turn off a motor aftera fixed number of rotations of said idler sheave in one direction, andafter said fixed number of rotations in an opposite direction, and afterany amount of rotations therebetween as desired.
 3. The boat lift systemof claim 1, further comprising a user interface to allow a user toinvoke the function of the programmable boat lift system.
 4. Aprogrammable boat lift system, comprising: a) a single idler sheavehaving a plurality of holes for the transmission of light, said idlersheave constructed to engage a single cable and to rotate on an axis asthe single cable moves across said idler sheave; b) a quadrature encoderhaving two pairs of IR transmitters and IR receivers, said encoderplaced over said idler sheave, said two pairs of IR transmitters and IRreceivers being set apart about 165 degrees relative to said axis ofsaid idler sheave; c) said IR transmitters transmitting infra red lightthrough the holes in said idler sheave and said IR receivers receivingsaid infra red light so that said encoder produces an electronic outputsignal in proportion to the number of rotations of said idler sheave,and in proportion to the distance the single cable travels over saididler sheave, as the single cable moves across said idler sheave; d) anelectronic control circuit having a microcontroller, an in-circuitprogramming header; and a motor control circuit, said control circuitprogrammable to use said output signal to infer the exact position ofthe single cable and the boat lift cradle without the requirement of alimit switch; and e) said electronic control circuit is programmable toautomatically turn off a motor after a fixed number of rotations of saididler sheave in one direction, and after said fixed number of rotationsin an opposite direction, and after any amount of rotations therebetweenas desired.
 5. The boat lift system of claim 4, further comprising auser interface to allow a user to invoke the function of theprogrammable boat lift system.